Radiation suppressor for internal combustion engine ignition system



April 18, 1967 H. M. DRESSEL 3,315,206

RADIATION SUPPRESSOR FOR INTERNAL COMBUSTION ENGINE IGNITION SYSTEM Filed Oct. 19, 1965 INVENTOR.

9 I HENRY/1!. aesssa 5 7 BY ArroRA/VS.

United States Patent 3,315,206 RADIATION SUPPRESSOR FOR INTERNAL COM- BUSTION ENGINE IGNITION SYSTEM Henry M. Dressel, St. Marys, Pa., assignor to Stackpole Carbon Company, St. Marys, Pa., a corporation of Pennsylvania Filed Oct. 19, 1965, Ser. No. 497,900 Claims. (Cl. 338-66) A radiation suppressor for insertion between an internal combustion engine ignition cable and a distributor is provided with a metal socket for receiving one end of the cable. The opposite end of the suppressor carries an electrical contact member for insertion in a distributor cap socket. The suppressor is provided with an axial passage containing a resistor and a coil spring engaging each other end-to-end and also engaging the metal socket and the contact member.

The ignition systems of motor vehicles produce electromagnetic radiations in the high frequency range of television broadcasting channels. Such radiations therefore interfere with nearby television reception and may also interfere with the proper functioning of other electronic apparatus. To help suppress such radiations it is common practice to provide spark plugs with internal resistors. This takes care of the plugs, but it does not prevent the ignition cables from radiating, due to sparking inside the distributor. Thus, the rotating distributor arm, which applies the ignition voltage to each spark plug in succession, does not make physical contact with the stationary contacts in the distributor, but establishes electrical connection through the air by a spark. This spark shock excites the distributor cable, which produces interfering radiations determined by its dimensions and location. A resistor in the spark plug cannot prevent this because such a resistor is located at the opposite end of the cable. Therefore, ignition cables have been formed from electrical resistance material throughout their length or from a string of separate resistors. Such cables have not always proved to be satisfactory for a variety of reasons, so it is preferred to use standard insulated wire cables, but of course standard cables will emit objectionable high frequency radiations.

It is an object of this invention to provide an internal combustion engine ignition system using standard ignition cables but which will not produce undesirable high frequency radiations. Other objects are to provide high frequency suppressors that can be quickly and easily inserted between the ignition cables and the distributor, and which are simple and inexpensive in construction.

In accordance with this invention an insulating plug is provided at one end with an axial opening containing a metal socket for receiving one end of an ignition cable. The plug has an axial passage extending through it from the socket to the opposite end of the plug. The exposed end of this passage is covered by a metal contact member that is attached to the plug. The contact member and adjoining portion of the plug are adapted to be inserted in one of the electric sockets in the cap of an internal combustion engine distributor. A radiation suppressing resistor and a compressed coil spring are disposed in endto-end engagement in the plug passage to form an electrical connection between the metal socket and the contact member. Consequently, the ignition cable will be connected to the distributor through the electrical resistor.

The invention is illustrated in the accompanying drawings, in which FIG. 1 is a fragmentary side view of a distributor cap with ignition cables connected to it;

FIG. 2 is an enlarged side view, partly broken away in vertical section of one of the suppressors inserted in a cap socket;

FIG. 3 is a still further enlarged longitudinal section of the insert alone, rotated degrees from the position shown in FIG. 2;

FIG. 4 is a side view of a modification; and

FIG. 5 is a lower end view of the suppressor shown in FIG. 4.

Referring to FIG. 1 of the drawings, a conventional molded insulation cap 1 of the distributor of an internal combustion engine, such as used in an automobile, truck or airplane, is provided on top with a number of sockets 2, to which are connected the ignition cables 3 from the spark plugs and coil of the engine. As shown in FIG. 2, in the lower part of each of these sockets there is a metal member 4 that extends down into the distributor and forms an electrical contact with which the distributor rotor makes electrical connection periodically. The upper end of the metal member is provided with a vertical bore 5. As is well known, the customary practice is to plug an ignition cable directly into the distributor socket.

According to this invention, however, the cables are not plugged into the distributor cap but are connected to it through electrical conducting units or suppressors that receive the cables and are inserted in the distributor sockets. The body of each of these suppressors is a tubular insulating plug 7, the lower portion of which is small enough in diameter to fit in a distributor socket. The upper portion of the plug above the distributor is larger in diameter, preferably being about the same size as the upper end of the distributor socket and resting on top of it. This enlarged portion of the insulating plug is provided with an axial opening in which a metal socket 8 is rigidly mounted. The metal socket generally will be about the same size and shape as the upper part of a metal member 4 in the distributor cap, so that a conventional ignition cable,'with the usual spring metal clip 9 (FIG. 2) on its lower end, can be plugged into the cap.

Extending from the metal socket 8 down to the lower end of the plug is an axial passage v11, the lower end of which is covered by a U-shape contact member 12 made of spring metal. This contact member straddles the lower end of the plug, with the legs of the contact extending upwardly along the plug. Normally, these legs diverge upwardly so that when the plug is inserted in the distributor cap the legs will be pressed toward each other by the walls of the distributor socket and thereby make good contact with metal member 4. To hold the contact member on the plug, the legs of the contact are provided with struck-out tongues 13 that extend laterally toward each other into radial holes 14 formed in the plug. Another tongue 15 is struck out of the base of the contact and extends up into the lower end of the plug passage.

The metal socket in the upper end of the plug is electrically connected with contact member 12 at the lower end by means of an electrical resistor 17 and a coil spring 18 disposed in end-to-end engagement in the plug passage. Preferably, the coil spring is below the resistor and supports it so that the base tongue 15 of the contact member can project up into the spring. The spring is compressed between the contact member and the resistor and thereby presses the resistor tightly against the bottom of metal socket 8. The lateral tongues 13 on the contact member prevent the spring from pushing it away from the plug.

A resistance value for the resistor is chosen that will suppress high frequency radiations from the ignition cable connected with it, without interferring with the proper functioning of the ignition system. The manner of determining such resistor values is well known and does not need to be explained here. When all of the distributor cap sockets are provided with the suppressor inserts just described, the ignition cables will cause little, if any, interference with television reception and other electronic apparatus that heretofore have been bothered by radiations from such cables.

In the modification shown in FIGS. 4 and 5, the metal contact member 20 at the lower end of the insulating plug 21 has a circular base and four laterally spaced legs. Two opposite legs 22 of the four are provided with inturned tongues 23, preferably by bending their upper ends toward each other. These tongues project loosely into radial holes 24 in the plug to lock the contact on the plug. A resistor 25 and a compressed coil spring 26 in the plug connect its metal socket 27 with contact 20. The other two legs 28 of the contact member are longer and are not provided with locking tongues. They normally diverge upwardly along the plug and serve to make good contact with the encircling Wall of a distributor cap socket when the plug is inserted in such a socket. The locking legs and the contact legs function independently of each other. With this construction, it also is unnecessary to have a tongue project upwardly from the base of the contact member, because the four legs prevent the base from moving laterally in any direction. However, such a tongue 29 may be useful for another purpose, which is to hold the outer end of the coil spring straight and in place as the contact member is applied to the plug and the spring is compressed.

According to the provisions of the patent statutes, I have explained the principle of my invention and have illustrated and described what I now consider to represent its best embodiment. However, I desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

1. A radiation suppressor for insertion between an internal combustion engine ignition cable and a distributor, comprising an insulating plug provided at one end with an axial opening, a metal socket rigidly mounted in said opening for receiving one end of an ignition cable and making electric contact therewith, the plug being provided with an axial passage extending therethrough from said opening to the opposite end of the plug, a metal electrical contact member overlying the exposed end of said passage and attached to the plug, said contact member and adjoining portion of the plug being adapted to be inserted in a distributor cap socket said member having a portion extending along the outside of the plug for making electrical contact with the side of the cap socket, and a compressed coil spring and a radiation suppressing resistor disposed in end-to-end engagement in said passage and forming an electrical connection between said metal socket and contact member which they engage.

2. A radiation suppressor according to claim 1, in which said contact member is a U-shape member of spring metal straddling the end of said plug and provided near its ends with tongues extending late-rally toward each other, the plug being provided with lateral holes receiving said tongues to hold said member on the plug.

3. A radiation suppressor according to claim 2, in which said resistor engages the metal socket, and said contact member is provided with a third tongue projecting into the adjoining end of the coil spring.

4. A radiation suppressor according to claim 1, in which said contact member has a base extending across the end of the plug and four laterally spaced legs extending along the plug, two opposite legs being provided with inturned tongues, the plug being provided with lateral holes receiving said tongues to hold said member on the plug, the other two legs of the contact member normally diverging away from said base and serving as spring contacts for engagement with the inside of a distributor cap socket.

5. A radiation suppressor according to claim 4, in which said resistor engages the metal socket, and said contact member is provided with a third tongue projecting into the adjoining end of the coil spring.

References Cited by the Examiner UNITED STATES PATENTS 2,487,098 11/1949 Carington et al 338-220 3,045,199 7/1962 Shobert 1 338-66 3,134,954 5/1964 'Bravn 338-66 RICHARD M. WOOD, Primary Examiner.

ANTHONY BARTIS, Examiner.

W. D. BROOKS, Assistant Examiner. 

1. A RADIATION SUPPRESSOR FOR INSERTION BETWEEN AN INTERNAL COMBUSTION ENGINE IGNITION CABLE AND A DISTRIBUTOR, COMPRISING AN INSULATING PLUG PROVIDED AT ONE END WITH AN AXIAL OPENING, A METAL SOCKET RIGIDLY MOUNTED IN SAID OPENING FOR RECEIVING ONE END OF AN IGNITION CABLE AND MAKING ELECTRIC CONTACT THEREWITH, THE PLUG BEING PROVIDED WITH AN AXIAL PASSAGE EXTENDING THERETHROUGH FROM SAID OPENING TO THE OPPOSITE END OF THE PLUG, A METAL ELECTRICAL CONTACT MEMBER OVERLYING THE EXPOSED END OF SAID PASSAGE AND ATTACHED TO THE PLUG, SAID CONTACT MEMBER AND ADJOINING PORTION OF THE PLUG BEING ADAPTED TO BE INSERTED IN A DISTRIBUTOR CAP SOCKET SAID MEMBER HAVING A PORTION EXTENDING ALONG THE OUTSIDE OF THE PLUG FOR MAKING ELECTRICAL CONTACT WITH THE SIDE OF THE CAP SOCKET, AND A COMPRESSED COIL SPRING AND A RADIATION SUPPRESSING RESISTOR 